


The Growth Experiment

by Rockinlibrarian



Series: The Loudermilk Chronicles [4]
Category: Legion (TV)
Genre: Backstory, Gen, I'm blanking, Identity Issues, Pre-Canon, Puberty, Self-Discovery, okay
Language: English
Status: Completed
Published: 2019-11-17
Updated: 2019-11-17
Packaged: 2021-02-07 13:03:16
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,769
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21458497
Author URL: https://archiveofourown.org/users/Rockinlibrarian/pseuds/Rockinlibrarian
Summary: In which the Loudermilk twins, age 13, conduct an experiment in order to figure out why Kerry's not growing properly, and in the process further define exactly where the line between them falls. And Mama comes to a bit of an understanding, too.
Series: The Loudermilk Chronicles [4]
Series URL: https://archiveofourown.org/series/1469729
Comments: 1
Kudos: 3





	The Growth Experiment

**Author's Note:**

> This is (finally) the story to which "The Personhood Hypothesis" is the prologue. I guess they're kind of the two parts of Kerry's self-development, with "Kerry and the Meaning of Life" the big defining moment in between.
> 
> Also, I had to make up a birthday for them, and even though I hold no stock in astrology, it seemed foolish NOT to make them Gemini...!

“Mama, if you didn’t know, how old would you say I am?”

Irma Loudermilk peered sideways in the direction of the girl who was apparently her daughter. She still wasn’t entirely sure Kerry wasn’t some mass hallucination her son had evoked during an identity crisis, and so she could never quite look her in the eye. But the answer had to be, “Thirteen, I guess.”

“I said if you _didn’t_ know!” Kerry protested. “You have to actually _look_ at me and say!”

Mama looked more directly, and found her eyes drawn past the girl to the boy she actually remembered giving birth to. “Why Cary, you’ve gotten so tall! I don’t think I’ve ever noticed before!”

The two children exchanged a dark look, and Cary sighed. “That’s the problem. I _haven’t_ gotten tall. All the girls in my class and most of the boys are taller than me now.”

“They are _older_ than you, too. Most thirteen-year-olds aren’t _in_ high school yet. But we can talk to the doctor if you’re worried.”

“It’s not me I’m worried about. It’s _Kerry_,” he gestured toward the girl with both hands to make clearer that he wasn’t talking about himself, “who’s stayed _short_. I know it’s common for boys not to hit puberty until they’re 15 or so, but the girls on the other hand….”

“The other kids think I’m _nine_,” Kerry whined, which did make her mother frown and look at her directly.

“What other kids? At jujitsu?” Kerry had been taking the jujitsu class at the YMCA in the city for the past year and a half. It was the first and only thing she’d been allowed to do on her own, by way of nobody there knowing she’d signed up using her brother’s records (the “gender” check box was a little smeared).

Kerry looked a little shifty. “Well, yeah, there….”

“Where else are other kids _seeing_ you?” 

“Not anywhere I have to _explain_ myself! Nobody cares who I am, they just think I’m Cary’s cousin from out of town or something. It’s not like I let them see me walking _out_ of Cary.”

“We’re very discreet,” Cary attested.

“Besides, _you_ don’t even believe in me half the time, why should the other kids worry about it?”

Mama sighed. “Right, sorry, you just… I just….” She smiled at Kerry directly. “I promise to try to believe in you all the time. Which means I suppose you and I should have our own girls-only version of The Talk soon.”

Kerry looked properly horrified. “That’s okay, Cary reads a lot.”

Half to distract from the embarrassing tension, and the revelation that he had read _Growing Up for Girls_, too, Cary said, “I still think it’s because you don’t eat. You don’t eat, you don’t grow, obviously.”

“But I don’t starve, either.”

“I-intriguing point. So, what do we know for sure?” Cary grabbed a pencil and the tablet from beside the phone and started to scribble a chart. Kerry rolled her eyes. Mama sat back and smiled, a mix of proud and amused. “Until we were eight years old, we must have grown at the same rate, because you were clearly also eight when you came out for the first time. But after that point, you’ve grown at a rate of approximately one year to every four I’ve grown, if we adjust for how _long_ you’ve looked nine, however— I’m really not sure how to pinpoint that more accurately.”

“A one to four ratio is close enough for now, and easy to work with,” Mama assured him.

“Okay. We also know that Kerry won’t eat, so, how is she still alive?”

“You make it sound like I don’t eat just to spite you,” Kerry complained. “It’s weird, and I’m fine, so why should I?”

“Sure, but _why_ don’t you need to? The most logical explanation is, I eat _for_ you. You absorb all your nutrients through me when we’re together. Up until we were eight years old, we were always together, so it follows you were always absorbing nutrients through me and so we grew together, too. But your growth slowed down once you started spending time outside me, so maybe that’s because you’re not constantly absorbing nutrients any more. So you’re getting enough not to starve, but not enough to grow fully?”

“I don’t mean to keep harping on this,” Mama said, “because it’s not that I don’t trust you, but exactly how much time _is_ she spending outside? I’m not prying, it’s just for the sake of your hypothesis.” She absolutely was prying, but the point was still valid.

“Well, let’s see. We’re asleep eight hours, we’re never apart for that, and there’s about two hours a day, maybe, you’re inside for meals and hygiene and all that, then, six hours for school—” he frowned. “The math doesn’t work. That already brings us up to three quarters of the day that you’re inside me, but you’re only growing at one-quarter the rate. I _knew_ we should have used more accurate numbers.”

“I’m not sure your estimate was far enough off to make that much of a difference. But I have no doubt you’ll figure out a way to test it.” Mama stood up and left them to it.

Part of Mama was still reluctant to get the point, though, and scheduled a doctor’s appointment just to allay Cary’s supposed fears about his own growth. As Cary had expected all along, the doctor found no cause for concern. “You’re not only about to get taller, you’re going to be _tall_. Looking at your early growth records and the size of your feet now, I’d say you’ll shoot up half a foot just in the next year.”

Cary’s mind whirled. “Is there any way you can… n-narrow down the time frame? Exactly when should this happen?” The doctor just laughed and reiterated that there was nothing to worry about. But Cary was only trying to set up a science experiment.

“If we know for sure I’m about to get noticeably taller, it’s the perfect time to test how much Kerry’s growth is linked.” Technically he told Mama this on the way home, but he was mostly directing it at Kerry, who was inside him then and couldn’t very well come out because they were still in public. Mama hated when he said “Kerry” in public, too, but he didn’t think anybody would be listening that closely. “We’ll chart it by inches. Inches _and_ pounds, in case there’s more growth than just height. More objective than trying to guess what age we _look_. We’ll measure both of us, using the same tools, and then…then, Kerry, you’ll just stay inside for the next six months, or at least until I’ve grown an obvious amount. Then we’ll measure again. Then, you go back to coming out whenever you want, and we’ll measure a third time after an equivalent amount of additional time passes.”

“So after we take the first measurements, I can’t do _this_ anymore?” Kerry said, taking advantage of the quiet side street they’d just turned onto to appear in between her mother and brother.

“Kerry!” Mama looked somewhat frantically around them for gawkers.

“Nobody saw,” Kerry retorted.

“Yes, but, I mean, how hard could that be?” Cary replied to the first question, utterly unfazed. “You did it for eight years straight.”

Kerry nodded. Even if it was funny to freak Mama out like this on occasion, there really wasn’t any place she’d _rather_ be than securely merged with Cary. How hard _could_ it be to stay there full-time again? But then she wondered, “Are you going to go to jujitsu for me?”

Cary made a face. “No. Why would I?”

“Because I…I guess I’ll have to quit otherwise?”

“Not permanently,” Mama cut in to reassure her. “We can enroll you again when you’re done with your experiment.”

Still, for the first time, the thought of _never_ leaving Cary started to worry Kerry. She had important things to _do_ on her own. “What if someone messes with you and I need to come out and beat them up?”

“What?” Mama said.

“No one’s messed with me since the time you knocked Clive Marrow’s teeth out,” Cary said.

“You _what_?” Mama said louder.

“He deserved it,” Kerry said quickly.

“And who did Clive Marrow tell his mother had knocked his teeth out?” At this point Mama had stopped walking and was glaring with her hands on her hips, looking rather like her daughter, to tell the truth.

Kerry looked at Cary and burst out laughing. Cary struggled to keep a straight face himself. “I believe,” he said, “his official story was that he’d had a ‘hockey accident.’ But several witnesses informed the rest of the school that it had really been ‘That Little Girl’.” By that point Kerry was giggling too hard for him not to join in.

“This is not a laughing matter!” Mama protested. “First of all, I don’t like you taking such glee in another’s injury, even if he _did_ deserve it—”

“Oh, he did,” Kerry interjected.

“Secondly, what if the Morrows had pressured him to tell who was really to blame? Even if you _were_ just ‘That Little Girl,’ the other kids _do_ know you have some connection to Cary, and people would have been around to ask questions, and next thing we know they’ll have dragged you both off to some…residential school, or hospital, or somewhere, probably run experiments on you—and not _your_ kind of experiments, either, Cary,” before he could say anything.

Neither of them had a decent comeback, but they did stop laughing. After a minute or so of somber silence, Kerry piped up, “Well, guess I can promise not to knock anybody’s teeth out for the next six months.”

“October 16,” Cary wrote in what used to be the tablet by the phone, but had now become the official log of The Growth Experiment. “13 years, 4 months. Cary: 61 in, 90 lb. Kerry: 52 in, 64 lb.”

“You sure you’re ready?” he asked her. “You understand you cannot come out until I’ve significantly grown, however long that might be.”

“Yes, yes, I get it,” Kerry said aloud, one last time, and flounced, for good measure, into her usual position. _Gee, what am I doing here? This is so unusual._

“Cut the sarcasm. Of course it’s easy _now_. But do you promise to _stay_ there?”

_Why are you talking to me, I’m already asleep. I’m FINE, Cary! Just keep… doing your boring thing, and I’ll do mine._

“But in there.”

_Yeah, I think I know how to spend my time in here better than you do._

And she did. For several days (perhaps? Kerry never had much of a sense of time, particularly not inside) she abided without a peep—not that the experiment demanded she be silent, but it added something to convincing Cary that she could do it. In fact it was Cary who broke first. “Kerry? Are you okay?”

_What. Yeah. Why wouldn’t I be?_

“Just checking.” He missed her, actually, but he was thirteen and it was getting harder to say that sort of thing aloud.

A few more…days?…passed before she gave in.

Apparently she’d missed talking to Cary more than she thought she would, because she talked enough for Cary to actually tell her to be quiet for a bit so that he could read. He had been sitting reading about covalent compounds or something for hours, or minutes, or long enough, and she couldn’t take it any longer. _I’m bored_.

“Try to see how far you can take the Fibonacci sequence,” he suggested, because come on, that could go on infinitely.

_1 1 2 _

“You forgot zero.”

Huge sigh. _ZERO 1 1 2 3 5 8 13 this is not not-boring!_

“Then what _is_ not boring?”

_Kickboxing._

He rolled his eyes. “Well that’s out of the question, you can’t right now. So you’re going to have to come up with something else.”

_But YOU can_.

“I can what?”

_Kickbox._

“No I can’t.”

_Have you ever tried?_

“No, but—”

_Then you can’t say you can’t._

“Kerry, I’m busy right now, I’m not going to—”

_You’re always sooooo busy, staring at molecules all day. You never asked what_ I _want to do!_

He sputtered a bit. “B-but you, you don’t—”

_I’m stuck doing whatever you want until you grow some, you could at least switch things up occasionally!_

Cary slipped a scrap of paper into his book and sighed. “What would you have me do, then?”

_…Calisthenics?_ Kerry wasn’t exactly sure, herself. She just wanted to _move_. She didn’t think she could talk Cary through kickboxing easily enough for him to do it _quickly_ enough for her wishes. After some stretches and jumping jacks, Cary was winded and Kerry was satisfied.

But the next day, calisthenics were not enough. _Go, keep going, go outside, let’s run! _

“You…you do re…recall,” Cary panted, “that I’m a-asthmatic?”

_Only when you’re emotionally worked up_, she countered. _So don’t freak out and we’ll be fine_.

“Cary?” Mama called as he stumbled toward the door. “What’s going on?”

“K-kerry wants…to…to run, I guess?” He closed the door behind him, leaving his mother momentarily confused over why he was speaking as if he had no control over his own body, her possibly-imaginary daughter having slipped her mind again in her absence.

Cary was getting unsure about Halloween with Kerry stuck inside, mainly because she started, a week before, running down all the possible warning signs of tricksters about to jump him, since she wouldn’t be able to intervene. “You know, I’m getting too old to go out anyway,” he finally said, even though he had brilliant plans for this year’s robot costume. “I’m a teenager now, and all.”

“And pass up this year’s robot costume?” Mama had always been a proud supporter of the annual brilliant robot costume.

_And candy, whyever you’d want that?_ Kerry got the hype about candy in _theory_, only. _Also, maybe build your candy sack into the robot costume so people will be less likely to snatch it._

“Kerry you’re not helping!”

“What?” Mama looked blank again.

“Kerry keeps talking like I’m going to get mugged.” As Mama still looked blank, he continued. “Girl-Kerry. She’s been staying inside so we can see how she grows?”

Mama paused, then nodded and said, “Oh! Oh yes. Of course.”

Kerry sighed. _I thought she believed in me now._

“Well, you _have_ been out of sight for the past two weeks.”

“I haven’t forgotten her, really.” Mama looked properly abashed. “I got into such a habit of _pretending_ she wasn’t there but… she did make that difficult.”

_I can be annoying THROUGH you if she wants! Then it will be like she can still hear me!_

“I don’t think it works that way. Not you, Mama. Kerry is offering to be annoying through me so you don’t forget about her.”

“Oh.” Mama bit her lip to keep it from curling too far upward. “I don’t think that will be necessary. So, is she letting you do Halloween or not?”

“I…think so?”

_Yeah, do it. If you need to kick anybody, I’ll talk you through it_.

Most of the time, it was easy enough to slip back into the old Kerry-as-voice-in-Cary’s-head existence they’d been living five years before. That’s how they spent most of their time, _still_, anyway. There were moments, like when they were watching TV and Cary’s attention would wander to a book nearby and Kerry would have to yell at him to keep his eyes on the screen, or, conversely, when Cary had spent too much time in the same place, that Kerry had to work very hard to keep herself from bursting outward. She’d taken for granted the freedom she used to have. Maybe she _preferred_ to spend all her time with Cary, but it still felt better to have the _option_ of stepping out occasionally.

She _may_ have taken a bit of advantage of Cary’s pushover nature those weeks. Whatever she asked him to do—assuming he himself believed he was capable of doing it (gymnastics were out, but she did eventually talk him into some pretty weak kickboxing)—he’d try, even if he complained or did it poorly. It was _almost_ like having agency still.

A snowstorm swept through in late November, nullifying their now-routine daily jog. _Oh, come on! We gotta clear the walk._

“Why? School’s canceled.” Cary had every intention to spend all day curled up in front of the fire with a book or four.

_It’s so stuffy in here!_

“In…me?”

_Yes. But also in the house. Let’s go. _

Cary groaned, but pulled on all his cold weather gear because he knew he’d never get peace by the fire anyway if he didn’t. “Kerry has a sick… and contorted… idea of fun!” he announced in between gasps after a few wet shovelfuls.

“I don’t have a problem with this,” Mama said from the doorway. “When you finish the sidewalk and the drive, come in and I’ll make you hot cocoa.”

_No, when you finish we can run!_

“This isn’t enough exercise for you?!”

She relented. He _was_ breathing awfully hard. _Okay, this time. At least we’ll have somewhere to run later. Unless it snows again. But if it’s just a _little_ more snow, then we ARE doing both! _She was sure he could handle _that_. His stamina had come so far since she’d made him start running.

Being that the winter holidays involved mostly eating and visiting relatives who didn’t know she existed, Kerry would have spent more time than usual inside Cary, anyway. It was a few days after Christmas before things settled down enough for Kerry to get antsy again. But this time it had nothing to do with being bored. This year, anyway.

Mama was at the kitchen table, transferring appointments, birthdays, and other important dates into the new year’s calendar from the bank, and that caught Cary’s attention. “Oh, guess what today is, Kerry! It’s exactly five years since you first came out.”

_Hah. I’d celebrate by coming out, except I’m not_ allowed.

“It is kind of ironic, isn’t it. But happy separate-birthday, anyway.”

Mama paused in her notekeeping and smiled wryly. “That was just after Christmas? I remember it much later in the winter, March or so.”

“That’s just when we told you about it,” Cary said. “I thought I was just imagining her for a long time, too.” _Which didn’t make ANY SENSE_, Kerry put in. “But she kept insisting she was real and that you were her Mama, so eventually I just had to know what _you_ knew.”

Mama laughed. “Nothing. I knew absolutely nothing.” She sighed. “I’m sorry it took me so long to believe you. Both of you. But since you’ve been doing this experiment it’s become clearer how much I’ve grown to…. She had just so much _energy_. Everything she did would take me by surprise and… I remember how she used to slip out behind me just to scare me. I miss her. Please let her know that.”

_Oh, Mama_.

“She can hear you, actually.” _I really want to jump out at her now._ “And she wishes she could scare you again right now.”

“I will take that as a compliment.”

It felt funny, being talked about as if she wasn’t still there. Mama did, truly, believe in her at last, and yet Kerry was stuck in observer mode, just as she used to be. _I’m not imaginary!_ she suddenly felt like proclaiming. _I am here, and I am always here! I am GIRL-KERRY, I am real, and I am tough! _

One day in early February, Mama said, “Holy cow, Cary, those pants were new at Christmas and I already need to let the hem out. What have you been eating?”

Cary dropped his bookbag where he stood. “That much? That much already?” He raced to the measuring wall they’d used since he was small. “Can…can you take an exact measurement? Now?”

Mama looked moderately bemused, but came over and reached up to pinpoint the numbers. “5'5." You’re officially taller than me, now, and still going.”

“Four inches.” _That’s enough, isn’t it?_ “Yes, we- we can work with that.”

A dark blur swirled out of him. “Freedom!” Kerry shouted, and sprinted the whole length of the house and back. Cary felt…slightly hurt at that. But she arrived back beside him and said, “You could never go fast enough.”

“Kerry.” Mama’s eyes had gone misty. “It’s good to see you again.”

Kerry’s puzzled frown slowly broke. “Yes! Yes it is.” Mama held out her arms and Kerry gladly hugged her.

Cary cleared his throat. “We have to take the measurements at the same time.”

“Two minutes is not going to make a difference in this case,” Mama said, but she did let go of Kerry.

Kerry seemed somehow even smaller to him than she had the last time he’d seen her. “4 feet 4 inches,” Mama read off the wall. “That’s—”

“That’s exactly what she was last time!” Cary squinted at the notes in the experiment log.

“I was going to say,” Mama said, “the line is in the exact same place. Not a smidgen off.”

“You mean after all that trouble I haven’t even grown any?”

“We still need to check weight,” Cary pointed out. “You could have grown _out_.” But he doubted it. And the scale confirmed it.

“Well that settles it, I guess.” Cary sat and wrote in the experiment log. “'Results of Phase 1: after just under four months, Cary has grown four inches and …seventeen pounds,' somehow.”

“Muscle weight! Jogging and snow shoveling! You put on muscle!” Kerry applauded. She took full responsibility.

“'But despite never once leaving Cary’s body, Kerry has remained exactly the same size. We will see if this changes in Phase Two,' although I don’t see how it can.” He frowned as if the experiment had hurt his feelings by making no sense. Which it probably had.

“Maybe I just needed to stretch.” She stretched then, as if to demonstrate. It felt good.

“Take all the stretching time you want,” Cary said. “Phase Two begins now.”

“All right, world. I am GIRL-KERRY. I am here, I am real, I am tough!”

“Okay.” Cary smothered a laugh. “So, wh-what are you going to do about that?”

Kerry narrowed her eyes and murmured, threateningly, “I haven’t decided yet.”

First she decided to run, but the house was small, so she threw open the door and started to run outside, but it was February in Montana, and she didn’t even own a coat. _Cary_ was her coat. She came back inside and shouted, “CARY!!”

“No way. I’m not running out there with you _any more_.” He rummaged in the closet and pulled out the coat he’d recently outgrown. She still ended up swimming in it. Cary found a long scarf and wrapped it around her entire upper body.

“This seems excessive,” Kerry muttered, muffled by muffler.

“I just want to keep you safe.” He tried to force a pair of mittens on her hands.

“That’s _my_ job.” She took the mittens and put them on herself.

“You can’t punch the weather. We need to use thermodynamic technology for _this_ kind of safe, so it _is_ my job. Okay, go. Run free.” He felt just a little sad as she raced out the door without him.

Kerry ran, relishing the bite of the wind that snuck through the cracks in the scarf—she _was so_ punching the weather! She was totally showing it who was boss! She added some twirls and cartwheels just because she could. A couple streets over she slipped on a patch of ice, and back home in his room Cary hissed, “ouch,” and rubbed his elbow, but Kerry dusted herself off and kept running, thinking that one of these days she was going to learn to fall like she meant it.

By the time she got home, Cary was waiting by the door. “What?” she asked him.

“Nothing.” He shrugged with his hands in his pockets. “I was just making sure, is all.”

“I’m fine.”

“I know.”

“You could come with me.”

“No.”

A few minutes later, it was her turn to give a resounding “No.” _I am here, I am real, I am tough_, she kept telling herself. _I am a PERSON who can do all the things PEOPLE do, all by MYSELF._ Then Mama set a plate of chicken and mashed potatoes in front of her, and the thought of being _people_ turned her stomach.

“You know,” she said cheerfully, “I have never eaten before, so starting now would add an unnecessary variable to our experiment.” She snapped instantly into Cary. _I’ll come out again when you’re done eating._

“But I won’t have digested anything, so I don’t know if it will do you any good?”

_I am willing to risk that!_

“I thought your original plan for Phase Two was that Kerry would go back to coming and going as she pleased, not that she had to spend all her time out, anyway.” Mama held out Kerry’s plate. “Do you want hers, by the way? You, at least, are growing, and I don’t want it to go to waste.”

“Yes, please.” Cary hastily scraped the extra plate onto his own. “And yes, that’s what we’d said. You do remember that, don’t you?” he directed to Kerry, and then back to Mama, “but maybe she’s just tired of me.”

_Not that, dummy! I just want to prove I can. That I’m real. I just have to draw the line at food, though_.

“So…no digesting, then.”

_Maybe a little? But then I’m going to watch_ Banana Splits _without once trying to read something at the same time! And then I’m going to—oh, it’s dark out already. Oh, let’s play a board game!_

Kerry managed to find something or another to do under her own power until bedtime. Mama said something about brushing teeth and Kerry said, “I didn’t eat anything!” and popped back inside for a few minutes, but soon she was back out saying, “Mama? Could we have an extra pillow and some blankets?”

“Really?” Cary choked a little.

“Yep. I’m here, I'm real. Twenty-four hours a day.” She made a little nest on the floor beside their—_his_—bed.

Cary watched her solemnly. “Oh- okay. Good night, then.” He set his glasses on the bedside table and switched off the lamp. Kerry mimed removing her own glasses, only because it seemed awkward not to have that routine before lying down. _And then…I guess I close my eyes?_ This was more complicated than she’d thought.

She’d always noticed that her own senses were far sharper than Cary’s were, that the world was bright and noisy and cold whenever she left him. But she could handle that when she was moving.

Now, lying in the dark, each little noise—the gurgling radiator, cars crackling over the road outside, the buzz of the television down the hall, Mama’s occasional sighs, an unidentified scurrying somewhere in the walls— poked at her. Smells—the musty afghan Mama had pulled from a closet for her, Cary’s gym shoes, the wood-paneled walls—shrieked to be identified. Worse, she felt…_everything_. There were drafts—warm from the radiator, cold from the window—but in between there was simply distance. The space between each piece of furniture. Each object around her bent the fabric of reality just enough so that it seemed to chant her own mantra back at her: _we’re here, we’re real, deal with us_. 

She wrapped the afghan as tightly around her as she could, like a cocoon. And still she felt exposed. _How can anybody sleep like this? Okay. I can do this. I am real, I am…I am here…I am…cold? _But she just stared through the blanket, shivering, and feeling more and more awake. Finally she sat up. “Cary?” she whispered.

He was awake, too. “I know,” he said. He reached out. She grabbed his arm and pulled herself over and in. Their heartbeats merged, and slowed, and then, finally, they could sleep.

Epilogue: after three months of doing everything _except_ eating and sleeping on her own, Kerry grew two inches, and most people started assuming she was ten. That would do for now. She was here, she was real, and she was exactly as much a part of Cary as she wanted to be.


End file.
